Improved drift



@uitrit taten datent ffrr.

JOHN EGLINV OF MANCHESTER, ENGLAND, ASSIGNOR TO THOMAS ALDRIDGE WESTON.

. Letters Patent No. 62,123, dated February 154, 1867.

IMPROVED DRIFT.

TO ALL WHOM 1T MAY. CONGERN:

Be it known that I, JOHN EGLIN, of Manchester, England, engineer, have invented certain new and useful Improvements in Drifts or Tools used forEnlarging Holesg und I do hereby declaro that the following is a full and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon.

My invention relates to improved drifts, of roumhsguure, and other forms, such as are used for enlarging holes for bolts, pins, rivets, keys, and the like, in metal plates, bars, shafts, or blocks, the object being generally to render them more eilicient, more easily driven, `und more capable of leaving thc holes in u smooth, nished condition than the drifts hitherto in use; and in order that my said invention, and the manner of performing the saine, may he properly understood, I have hereunto appended a sheet of explanatory drawings, to he hereL inafter referred to, und representing examples of my improved drifts.

In making a drift according lto my said invention, e steel blank is taken, of a round, squarcfor other required transverse section, and having the usual slight taper longitudinally, and a series of grooves are cut contiulb ously upon it in equally inclined and opposite directions, so as to form a series of diamond-shaped cutters upon thesurface. i Y

Figure 1 is an eleva-tion; and

Figure 2, a plan of a round drift formed in this Way.

Figure 3, an eleva-tion; and

Figure 4, a plan of an oval drift.

Figures 5 and 6 are similar' views of a square drift; and

Figures 7 and 8 arc elevation and planof a ilattdrift.

v A fen' of the diamond-shaped cutting points, formed bythe grooving, are marked with the reference letter a. One side of each groove forms an obtuse angle with the surface, whilst the other side forms therewith a. rectangular, or nearly rectangular, cutting-edge, it being preferred to make this cutting-edge slightly more acute than a right angle'. If the drifts are for round holes, they may be conveniently and expeditiously formed in an ordinary lathe, by taking the blanks, prepared as usual of a tapering form, and cutting thereon a series of continuous inclined grooves in one direction; then reversing the endsof the blank, and cutting a second series of like inclinations in the opposite direction, thereby crossing the former series, and producing, by their numerous intersections, series of double-edged diamondfpointed cut-ters, which cover the whole surface. If of square or oblong form-,the'groopes are more conveniently formed by planing or filing, but their angle of intersection and their continuity may be the saine. This angle may vary with the purposes for which the tool is used, according-to the texture and hardness of the metal on which it is employed; but as a general rule the angle of forty-five degrees `is found preferable. The advantages of my improvement are, that drifts so formed cut with greater ease than the plain, continuous cutting-edges of ordinary drifts, because the points of the diamond t cutters (1,V being t-hc Vfirst to enter the metal operated upon, moet with slight resistance because of their small sizeg-and the cutting, once commenced, is continued by their diverging edges with easy gra-dation, and, cutting equally on both angles, there is no tendency of the drift to twist in the hole, orto deviate from its right direction; and, consequently, the hole is not distorted, but a perfect counterpart of the section of the tool. Itis obvious that the total length of the cutting-edges, when formed in this manner, is nearly double that of a. drift having a single series of grooves und cutting-edges in one direction only; consequently less Aforce is required, und a smoother and more finished hole is produced. This construction enables the drift to be used as a reculer, by rotation in the holc to be enlarged, as it is obvious that the angular cutting edges n'ill cut equally `Well in a horizontales in a vertical direction, and alsov equally in opposite directions,iso that the rotation may be reciprocal or vibrating, by ineens of a hand-lever or otherwise, with equally good effect.

Whnt I eluiln as my invention, and desire to secure by Letters Patent, is-

Forming tht` cutting-edges of drifts of a series of double-edged diamond cutters, by the intersection of two series ot' spirally-inelined grooves, in opposite directions, substantially :tsand for the purposes set forth.

Donc :it Manchester this 22d dny of June, 1866.

JOHN EGLIN.

Witnesses:

EDWARD J Usern Hennes, .Patent Agent, 2O Cross Street, Manchester. C. Serrures HUGHES, Patent Agent, 20 Gross StreegManczster. 

